On 6/3/17 2:38 PM, Poul-Henning Kamp wrote:
> --------
> In message <CABXq0ZCZLhBjpZwt+JTXTgR+xGPraO9x9ewKWXs+JAYe2h87Sw at mail.gmail.com>
> , "Donald E. Pauly" writes:
>>> Electronic thermal coolers did not exist then
>>http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html
I'm not sure about fancy coolers.. Yeah, people showed that the effect
worked, but I think they really didn't come into their own until the
modern ones that are omnipresent in 12V powered beer coolers and the
like were developed. That was 70s according to the article.
Borg Warner (of clutch, brake, and gearbox fame) apparently had one in
1960.
http://www.thermoelectric.com/2010/archives/library/Ads%20in%20the%2060's.PDF
So they existed, but were pretty exotic. would a crystal oscillator
builder have wanted to fool with one? Hey, there have been people
tinkering with almost everything forever.
>>> Electronic temperature sensors did not exist either.
>>https://en.wikipedia.org/wiki/Resistance_thermometer#History>
Yep... and thermocouples have been used for thermometry for a long time
too. Thermistors, for that matter, nonlinear as all get-out, but readily
available.
In the 50s, a *transistor* oscillator would have been pretty unusual.
I'm not sure they could work at a high enough frequency. You'll note
that the early "transistor radios" were basically TRF designs for the AM
band, and the transistor basically provided audio gain, not RF gain.
http://www.junkbox.com/electronics/sheets/GE_2N107_Datasheet.jpg
I guess the regen receiver must have had some gain at 1 MHz. I found an
old GE datasheet that gives the ft of 0.6 MHz. (and the hfe wasn't bad,
20, at DC, probably)
But you sure weren't building a 5MHz or 10 MHz oscillator with a 2N107
or a CK722. Or the 2N170 NPN, which I am surprised to find you can
still buy (and cheaper, in constant dollars, than originally).